Master information support

ABSTRACT

A master information carrier with excellent durability is provided, for the use of static and a real lump-sum recording of digital information signals on magnetic recording medium. The master information carrier comprises a non-magnetic substrate on which a ferromagnetic film is disposed with an embossed pattern. Protrusions of the embossed pattern correspond to a disposition of the digital information signals. 
     Recessed portions of the embossed pattern of the ferromagnetic film are filled with non-magnetic solid material. Alternately, A non-magnetic substrate has an embossed pattern and recessed portions of the embossed pattern correspond to a disposition of the digital information signals. A ferromagnetic film is filled in the recessed portions of the embossed pattern.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a master information carrier used for staticand areal lump-sum recording of digital information signals on amagnetic recording medium.

2. Description of the Related Art

A magnetic reading and reproducing apparatus has been increasing inrecording density to realize a small size and large capacity.Especially, in the field of a hard disk drive as a typical magneticrecording device, an a real recording density of more than severalgigabits per square inch is already available on the market. Further anareal recording density of ten gigabits per square inch is expected infew years.

One of the primary factors that has enabled such high recording densityis the increasing linear recording density, due to improvements ofmedium properties, head-disk interface performance, and a new signalprocessing method such as “partial response”. However recently the rateof increase-in track density exceeds that of linear recording density,and thus becomes a primary factor for increasing areal recordingdensity. Practical use of a magneto-)resistive type head, which issuperior to a conventional inductive type head in reproduction outputperformance, has contributed to the progress in the track density. It ispossible at present to read a signal from a track whose width is at mostonly a few microns with-good S/N ratio by practical use of themagneto-resistive type head. Further it is expected that a track pitchwill reach the sub-micron range in the near future along with furtherimprovement of the head performance.

A tracking servo technique is important for the head to read a signalwith high S/N ratio by scanning precisely such a narrow track. Forexample, a conventional hard disk has areas that are located atpredetermined angular intervals over 360 degrees. In those areasinformation such as a tracking servo signal, address and clock signal isprovided (hereinafter referred to as ‘preformat’). A magnetic head canscan a track by reading such information at predetermined periods, andmonitoring and correcting the head position.

The above-mentioned tracking servo signal, address and clock signal areto be reference signals for the head to scan a track precisely.Therefore, precise record positions are required for these informationsignals. Current preformat recording into a hard disk is performedprecisely by magnetic heads placed in the hard disk drive by using aspecial servo-track recording apparatus after installing the disk intothe drive.

The above-mentioned preformat recording using such a special servo-trackrecording apparatus has some problems as follows.

The first problem is due to the fact that relative movement between thehead and the recording medium is necessary for recording with themagnetic head. This fact means that a substantially long period isrequired for preformat recording. In addition, the special servo trackrecording apparatus is expensive. Thus, the cost for preformat recordingis quite high.

The second problem is that due to a space between the head and a mediumor due to a diffusive recording magnetic field caused by a pole shape ofthe recording head, the magnetic transition at track edges of therecorded preformat signals lacks steepness. In a current tracking servotechnique, the head position is detected by the amount of change in aread signal amplitude when the head missed a track. Therefore, thesystem requires a steep off-track performance, in which reproducedsignal amplitude changes sharply as the head misses the track Thediffusive recording magnetic field acts against this requirement, andthus, makes it difficult to realize a precise tracking servo techniquethat is required for a submicron track recording.

In order to solve the above-mentioned problems in preformat recordingwith a magnetic head, Japanese Laid-open Patent Application Tokkai Hei)10-40544 discloses a new preformat recording technique. In thedisclosure, a master information carrier comprising a substrate havingan embossed pattern on it is prepared The pattern corresponds to thepreformat information signal. At least the protruded portion of theembossed pattern is made of a ferromagnetic material layer. Bycontacting the surface of the master information carrier with thesurface of a magnetic recording medium and applying a magnetic field,the preformat information is recorded in the magnetic recording mediumas a magnetized pattern corresponding to the embossed pattern.

According to the disclosure of Tokkai-Hei 10-40544, a ferromagnetic,material composing the protruded portion of a master information carriersurface is magnetized by the applied magnetic field. By the recordingmagnetic field generated from the magnetized ferromagnetic material, themagnetized pattern corresponding to the embossed surface is recorded ona magnetic recording medium. Thus, the preformat recording of thetracking servo signal, address information signal, read clock signal andother signals is achieved by using the embossed pattern formed on thesurface of the master information carrier.

While relative movement between the head and the medium is required forconventional linear recording with a head, the technique of Tokkai Hei10-40544 is characterized by a static and areal lump-sum recording thatdoes not require relative movement between a master information carrierand a medium. As a result, the technique disclosed in the reference isgenerally effective for the problems related to preformat recording asfollows:

First, the time needed for the preformat recording is substantiallyshorter as compared to the prior art using a magnetic head. In addition,an expensive servo-track recording apparatus is not necessary forprecise position control of the magnetic head. Therefore, the techniquedisclosed in the reference can improve the productivity of the preformatrecording and reduce production costs.

Secondly, a space gap between the master information carrier and themagnetic recording medium can be minimized, since relative movementbetween them is not required for recording the information signal. Inaddition, the recording magnetic field for recording does not diffuse,unlike the prior art using a magnetic head. Thus, the magnetictransition at track edges of the recorded preformat signal is steepcompared with the recording with a magnetic head. This ensures a precisetracking of a magnetic head in reading data signals from the magneticrecording medium.

In the signal recording process of this technique, the masterinformation carrier and a magnetic recording medium should be contactedwith each other securely and uniformly over a large area. Tokkai-Hei10-269566 discloses a specific recording apparatus to meet thisrequirement with a function of sucking air between the masterinformation carrier and the magnetic recording medium to secure thecontact between them with the pressure of the surrounding atmosphere.

Tokkai-Hei 10-40544 discloses a master information carrier comprising asubstrate on which an embossed pattern corresponding to informationsignals is formed precisley by means of photolithography or the like,and at least the protruded portion of the embossed surface is made of aferromagnetic material. The master information carrier, however, will besubjected to partial stress intermittently and repeatedly when thepreformat recording is performed from the process of sucking air betweenthe master information carrier and magnetic disks being repeated tocontact them securely under the pressure of the surrounding atmosphere,by using the recording apparatus disclosed in Tokkai-Hei 10-269566.

Specifically, as the ferromagnetic material at the protruded portioncontacts directly and repeatedly with the magnetic disks, theferromagnetic material will be chipped gradually to lose accuracy in theembossed shape. When the chipping of the ferromagnetic material becomesserious, the recording signals will be lost or the magnetic disks willbe damaged.

In view of these facts, the master information carrier disclosed inTokkai-Hei 10-40544 requires improved durability. The master informationcarrier is required to allow repetition of good preformat recordingwithout losing recording signals or damage to the magnetic disks, i.e.,the master information carrier should have a long life, because the lifeaffects the number of recordings that can be made using the masterinformation carrier.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems of conventional techniques, itis an object of this invention to provide a long-life master informationcarrier having excellent durability for the repetition of recordingsteps involving pressure-contact with a magnetic recording medium.

A master information carrier with a first type configuration of thisinvention comprises a non-magnetic substrate on which a ferromagneticfilm is provided in an embossed pattern Protrusions of the embossedpattern composed of a ferromagnetic film correspond to a disposition ofdigital information signals. Recessed portion of the embossed pattern isfilled with a non-magnetic solid material.

A master information carrier with a second type configuration of thisinvention comprises a non-magnetic substrate having an embossed pattern.Recessed portion of the embossed pattern corresponds to a disposition ofdigital information signals. A ferromagnetic film is filled in recessedportion of the embossed pattern.

According to the present invention, the embossed pattern of theferromagnetic film is protected by the non-magnetic material, and theedge portion of the ferromagnetic film's pattern is hardly chipped.Therefore, the master information carrier can have an improveddurability and a long life, i.e., the number of times of recording perone master information carrier can be increased. As a result, thetechnique for static and areal lump sum recording disclosed inTokkai-Hei 10-40544 and Tokkai-Hei 10-269566 can be conducted at a stilllower cost with a still higher productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view showing a master information carrieralong the direction of bit length in the first embodiment of theinvention;

FIG. 2 is a cross sectional view showing a master information carrieralong the direction of bit length in a variation of the first embodimentof the invention;

FIG. 3 is a cross sectional view showing a master information carrieralong the direction of bit length in the second embodiment of theinvention;

FIG. 4 is a cross sectional view showing a master information carrieralong the direction of bit length in the third embodiment of theinvention;

FIG. 5 is a cross sectional view showing a master information carrieralong the direction of bit length in a variation of the third embodimentof the invention;

FIG. 6 is a cross sectional view showing a conventional masterinformation it carrier along the direction of bit length; and

FIG. 7 is a plan view showing an example of a pattern of a ferromagneticfilm formed on a master information carrier according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 7 shows an example of a configuration of a ferromagnetic filmpattern formed on a master information disk according to the presentinvention. This figure shows a master information pattern to be recordedin a preformat area of a magnetic recording disk that occupies tentracks in the radial direction, i.e., the track width direction, of thedisk. The preformat area is disposed at a predetermined angular intervalalong the circumferential direction of the disk, i.e., the track lengthdirection. In FIG. 7, areas defined by broken lines correspond to tracksto be used as data areas 10 in the magnetic recording medium afterrecording the master information signal. In the real master informationcarrier, such master information patterns shown in FIG. 7 are disposedat a predetermined angular interval and in all tracks over the wholerecording area of the magnetic recording disk.

The master information pattern comprises a tracking servo signal area11, a clock signal area 12 and address signal area 13 that are disposedsequentially along the track direction as shown in FIG. 7. The masterinformation carrier according to the present invention has a patternformed with a ferromagnetic film to correspond to the disposedinformation pattern. Each rectangle member with hatching is made, forexample, of a ferromagnetic film.

In the following first to third embodiments, the areal configurationexemplified in FIG. 7 can be provided respectively.

First Embodiment

FIG. 1 shows a cross section of a master information carrier with afirst type configuration in the bit length direction (track lengthdirection) taken along a phantom line A—A′ in FIG. 7. A ferromagneticfilm 1 with a fine embossed pattern is formed on a non-magneticsubstrate 3. In recessed portions of the embossed pattern of theferromagnetic film 1, a non-magnetic solid material 2 is filled. FIG. 6shows a conventional master information carrier disclosed in Tokkai-Hei10-405446 for comparison with FIG. 1. In the conventional example shownin FIG. 6, no material is filled in the recessed portions of theembossed pattern of the ferromagnetic film 1.

The master information carrier shown in FIG. 6 can be formed, forexample, by depositing a ferromagnetic film 1 on a planar non-magneticsubstrate 3, then applying a photoresist film thereon, then exposing anddeveloping the photoresist film to be embossed in a patterncorresponding to digital information signals, and subsequently carryingout a dry-etching such as an ion-milling to form a fine embossed patternon the ferromagnetic film 1, followed by removal of the remainingphotoresist film.

When the conventional master information carrier shown in FIG. 6 isrepeatedly used for recording on magnetic recording medium, partialstress is applied repeatedly and intermittently, especially to the edgesof the protruded portion of the ferromagnetic film surface. As a result,the edges of the ferromagnetic film pattern will be chipped gradually,and the accuracy of the embossed pattern will be lost. When the chippingof the ferromagnetic film is serious, the recording signals may be lostin the end.

In the master information carrier with the first type configurationshown in FIG. 1, the edges of the ferromagnetic film 1 are protected bythe non-magnetic solid material 2. Therefore, partial stress applied tothe edges of the pattern of the ferromagnetic film 1 when the masterinformation carrier is contacted securely and repeatedly with magneticdisks for recording by using the atmospheric pressure is relieved, andthus, the ferromagnetic film 1 can be prevented from being chipped. As aresult, one master information carrier can be used for the recording ofa considerable number of disks-compared to conventional masterinformation carriers, and thus, the life of the master informationcarrier can be extended.

The master information carrier with the first type configuration shownin FIG. 1 can be manufactured, for example, by the following steps of:

-   -   depositing a ferromagnetic film 1 on a planar non-magnetic        substrate 3 and applying a photoresist film thereon;    -   exposing and developing the photoresist film to provide an        embossed pattern corresponding to digital information signals;    -   forming a fine embossed pattern on the ferromagnetic film 1 by a        dry-etching such as an ion etching, using the patterned        photoresist film as a mask;    -   depositing a non-magnetic solid material 2 by any application        technique such as vapor deposition including sputtering and        vacuum evaporation, plating, or spin-coating; and    -   removing with a chemical solution the remaining photoresist film        and a extra non-magnetic solid material layer deposited thereon.        The chemical solution treatment can be replaced by mechanical        polishing.

In order to minimize the partial stress applied to the ferromagneticfilm 1 and maximizing the effect in preventing the chipping, theferromagnetic film 1 and the non-magnetic solid material 2 preferablyhave the same thickness to minimize the difference between them so thatthe surface of the master information carrier becomes flat.

The material used as the non-magnetic solid material 2 for the masterinformation carrier with the first type configuration preferably has alow solid-solubility with the material of the ferromagnetic film 1. Whenthe materials have a high solid-solubility with each other, the magneticproperty of the ferromagnetic film 1 will deteriorate due to diffusionat the interface between the ferromagnetic material 1 and thenon-magnetic solid material 2. It may degrade the recording performanceof the master information carrier. In general, the ferromagnetic film 1is made of Co, Fe, or an alloy comprising mainly these metals.Therefore, suitable materials having a low solid solubility with thesemetal films include films of oxides such as SiO2 and Al2O3, and metalfilms such as Cu, Ag, or an alloy mainly comprising these metal. Thesefilms can be formed by vapor deposition such as sputtering and vacuumevaporation.

Polymer materials such as polyimide can also be used for thenon-magnetic solid materials. Such a polymer layer can be formed, forexample, by diluting a commercially-obtainable polyimide solution with asolvent like cyclohexanol to have a proper concentration, applying thesolution with a spin-coater before curing at a high temperature. Sincethese polymer materials are resilient or flexible, the non-magneticsolid material 2 containing these materials functions as a buffer in therecessed portions of the ferromagnetic film 1. As a result, the partialstress applied to the edges of the ferromagnetic film at recording canbe relieved more efficiently.

The master information carrier with a first type configuration can havea longer life by forming a hard protective film 4 on the ferromagneticfilm 1 and non-magnetic solid material 2, as shown in FIG. 2. However,the hard protective film 4 cannot be too thick, since the gap betweenthe master information carrier and magnetic recording medium isincreased at signal recording, and spacing loss will be increased. In apreformat recording on magnetic disks as a typical application exampleof the invention, the recording wavelength of the signals is typicallyabout 0.3 μm or more. The allowable thickness for the hard protectivefilm is about 20 nm or less in view of recording spacing loss for therecording wavelength. Even for a thickness within that range, the lifeof a master information carrier can be extended sufficiently.

Films suitable for the hard protective film 4 include a C film, a Bfilm, an SiO2 film and the like in view of the hardness. These films canbe formed by a normal vapor deposition such as sputtering or vacuumevaporation.

When the hard protective film 4 has some electric conductivity, thereliability at recording can be further improved. A master informationcarrier covered with an insulating material will gather dust particlesdue to static electricity. Since these dust particles will increase gapsbetween the master information carrier and magnetic recording medium atrecording, resulting in deterioration of the recording performance, theyshould be removed properly prior to contacting the master informationcarrier with the surface of the magnetic recording medium.

Since a conductive hard protective film 4 gathers less dust particlesdue to static electricity, removal of dust particles can be simplifiedand reliable recording can be obtained easily. From this point of view,a C film fabricated by sputtering is the most suitable for the hardprotective film 4, since such a film has a sufficient hardness requiredto be a protective film and a conductivity to control dust adhesion.Although a B film and an SiO2 film have sufficient hardness, they cannotprovide sufficient effects to prevent dust adhesion because of theirhigh insulating properties. Another kind of C-based film comprising adiamond structure, fabricated by a method such as plasma CVD is harderthan a sputtered carbon film. However, it cannot provide considerableeffects to prevent adhesion of dust particles because of its relativelyhigh insulation properties.

Second Embodiment

FIG. 3 shows an example of a cross section of a master informationcarrier with a second type configuration in the direction of bit length(track length direction) taken along a phantom line A-A′ in FIG. 7. Inthis configuration, the ferromagnetic film 1 is embedded in the recessedportions of the non-magnetic substrate 3. The recessed portions of thenon-magnetic substrate 3 have a pattern corresponding to the dispositionof digital information signals, so that the embedded ferromagnetic filmis also patterned to correspond to the digital information signals.

In the master information carrier shown in FIG. 3, the edges of theferromagnetic film 1 are protected by the non-magnetic substrate 3.Therefore, partial stress applied to the edges can be relieved when themaster information carrier is contacted repeatedly and securely with themagnetic disks by using the atmospheric pressure, and thus, theferromagnetic film 1 can be prevented from being chipped. As a result,similar to the first type configuration, one master information carriercan be used for a considerable number of times of recording mediacompared with a conventional configuration, and thus, the masterinformation carrier can have a longer life.

The master information carrier with the second type configuration shownin FIG. 3 can be manufactured, for example, by the following processcomprising the steps of:

-   -   applying a photoresist film on a planar non-magnetic substrate        3;    -   exposing and developing the photoresist film to form an embossed        pattern corresponding to digital information signals;    -   forming a fine embossed pattern on the non-magnetic substrate 3        by a dry-etching process such as an ion etching, using the        patterned photoresist film as a mask;    -   depositing the ferromagnetic film 1 by any suitable techniques        such as vapor deposition including sputtering and vacuum        evaporation, or plating; and subsequently    -   removing with a chemical solution such as a remover the        remaining photoresist film and the extra ferromagnetic film 1        deposited thereon. The chemical solution treatment can be        replaced by mechanical polishing. Alternatively, the chemical        solution treatment and polishing can be carried out at the same        time.

Similar, to the first type configuration, a thickness of theferromagnetic film 1 is preferably matched with a depth of the recess ofthe non-magnetic substrate 2 in order to minimize the surface heightdifference at the interface and to flatten the master informationcarrier surface at this portion, for minimizing the partial stressapplied to the ferromagnetic film 1 and maximizing the effect inpreventing chipping.

In the second type configuration, the material used as the non-magneticsubstrates 3 preferably has a low solid-solubility with the material ofthe ferromagnetic film 1. When the materials have a highsolid-solubility with each other, the magnetic property of theferromagnetic film 1 deteriorates due to diffusion at the interfacebetween the ferromagnetic material 1 and the non-magnetic substrate 3.It may degrade the recording performance of the master informationcarrier. Moreover in view of industrial value, a substrate is preferablyselected from materials sufficiently supplied at a low price.Non-magnetic substrate materials meeting the above requirements includeoxides such as SiO2 and Al2O3, Si, and C.

When forming an embossed pattern on the non-magnetic substrate 3 bydry-etching with the above-mentioned substrate materials, a properreactive gas can be introduced for processing by reactive ion etching.The reactive ion etching is remarkably superior to a normal ion etchingusing no reactive gas in easy control of anisotropy and speed of theetching. So the reactive ion etching can provide an additional effect,that is, a pattern can be formed in a faster and accurate manner. Forexample, a CF₄ gas can be used as a reactive gas when the non-magneticsubstrate comprises Si.

In this case, the photoresist film can be replaced by a Cr film as amask for etching. Namely, an embossed pattern composed of a Cr film andcorresponding to digital information signals is formed on thenon-magnetic substrate 3 to etch the non-magnetic substrate 3 by usingthe Cr film as a mask. When the non-magnetic substrate 3 comprising Sior the like is processed by reactive ion etching, the Cr film isremarkably superior to a photoresist film in selectivity. As a result,the Cr film functioning as a mask can be thin compared to a photoresistfilm, and thus, the pattern can be formed with improved precision. Whena Cr film is used as a mask, the Cr film and the unnecessaryferromagnetic film thereon are difficult to remove by treating only witha chemical solution like a remover after forming the ferromagnetic film1. Mechanical polishing, or chemical polishing such as chemicalmechanical polish (CMP) should be conducted.

Third Embodiment

FIG. 4 shows a cross section of another master information carrier withthe second type configuration in the direction of bit length (along aphantom line A-A′) of the ferromagnetic film pattern shown in FIG. 7.

The feature of the configuration shown in FIG. 4 is that thecross-sectional shape of the ferromagnetic film 1 in the direction ofbit length is a substantial trapezoid with an upper side at the surfaceand a lower side on the substrate, where the upper side is longer thanthe lower side. Such a master information carrier can improve therecording performance remarkably. The reason can be explained asfollows.

When signals are recorded in an inplane magnetic recording medium, theferromagnetic film 1 of the master information carrier is magnetized inthe direction of bit length (the lateral direction in FIG. 4) of thefilm plane, and generates leakage flux from the slopes and both edges ofthe lower and upper sides of the trapezoidal cross section.Particularly, the flux leaked from the vicinity of the upper edges tothe master information carrier surface contributes to the recordingmagnetic field into the magnetic recording medium. The recordingperformance of the master information carrier is affected by theintensity of the recording magnetic field generated by the ferromagneticfilm 1 and also the magnetic field gradient in the vicinity of the upperedges at the ferromagnetic film surface.

If the upper side of the ferromagnetic film 1 is shorter than the lowerside in the cross section, the sloped sides of the film's edges willface to the surface of the master information carrier. In such a case,leakage flux generated from these sides will reach the surface of themaster information carrier and act as a recording magnetic field,resulting in the lowering of magnetic field gradient in the direction ofthe bit length in the vicinity of the upper edges at the ferromagneticfilm surface. In the embodiment shown in FIG. 4 where the upper side islonger than the lower side, the sloped sides at the edges of theferromagnetic film face toward the substrate (the lower part in FIG. 4).In this case, the leakage flux generated from the sloped sides cannoteasily reach the surface of the master information carrier. Therefore,at the interface with the non-magnetic substrate material in thevicinity of the upper edges, a steep magnetic field gradient can beconstantly obtained, and thus, excellent recording performance can beprovided.

Moreover, when the upper side is longer than the lower side in the crosssection, the magnetic flux is considered to concentrate easily at theupper side rather than the lower side in the vicinity of the edges ofthe ferromagnetic film 1 in the direction of the bit length (the lateraldirection in FIG. 4). As a result, leakage flux from the vicinity of theupper edges is increased compared to ferromagnetic films withrectangular cross sections shown in FIGS. 1-3, and thus, sufficientrecording performance can be obtained easily.

In a master information carrier having the first type configuration, anon-magnetic solid material 2 should be filled in the recessed portionsof the ferromagnetic film pattern after patterning the ferromagneticfilm 1. If the ferromagnetic film 1 is a trapezoid in the cross sectionas mentioned above, it may be difficult to fill the non-magnetic solidmaterial 2 without leaving gaps in the recessed portions of theferromagnetic film pattern in order to obtain sufficient durability.According to the embodiment of FIG. 4, such a ferromagnetic film with atrapezoidal cross section can be obtained more easily than the firsttype configuration.

FIG. 5 shows an example of a master information carrier basically havingthe configuration shown in FIG. 4, where a hard protective film 4 isfurther formed on the surface of the ferromagnetic film 1 andnon-magnetic substrate 3. Similar to the first embodiment, a masterinformation carrier with this configuration can have a longer life dueto a hard protective film 4.

Durability was evaluated for the master information carriers with theconfigurations exemplified in the first to third embodiments and amaster information carrier having the conventional configuration shownin FIG. 6, by repeatedly recording signals with the recording apparatusdisclosed in Tokkai-Hei 10-269566. As a result, the master informationcarrier with the conventional configuration shown in FIG. 6 had a lossof the signals after about 5,000 times of recording. Signals were notlost even after 50,000 times of recording for the master informationcarriers shown in FIGS. 1, 3, and 4, or even after 100,000 times ofrecording for the master information carriers shown in FIGS. 2 and 5 ofthis invention. This evaluation showed that the configurations of thisinvention can improve the durability of master information carriers andprovide a long life regarding the number of recordings.

This invention can be applied to various kinds of apparatus. While theabove description is focused on applications of magnetic disk installedin hard disk drives or the like, this invention is not limited theretobut can be applied to magnetic recording media such as flexible magneticdisks, magnetic cards, and magnetic tapes or the like to attain similareffects.

With regard to information signals recorded in the magnetic recordingmedium, the description of this invention is focused on preformatsignals such as tracking servo signal, address signal, and read clocksignal. This invention, however, is not limited thereto but can be usedin principle to record various data signals and audio and video signals.In such a case, recorded magnetic disks can produced on a large scaleeasily by using the technique to record on magnetic recording mediumwith the master information carriers of this invention in order toprovide them at a low cost.

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof The embodiments disclosed inthis application are to be considered in all respects as illustrativeand not limiting. The scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

1. A master information carrier used for recording information signalson a magnetic recording medium, comprising a non-magnetic substrate; apattern of a ferromagnetic film which is disposed on the surface of thenon-magnetic substrate, the pattern being disposed in the track lengthdirection so as to correspond to uniform and non-uniform arrangements ofthe information signals; and a non-magnetic solid material filled inportions between respective neighboring ferromagnetic film areascomposing the pattern, top surfaces of the ferromagnetic films and thenon-magnetic solid material forming a substantially flat surface,wherein the ferromagnetic film comprises a material selected from thegroup consisting of Co, Fe, and an alloy comprising Co or Fe as the maincomponent, and the non-magnetic solid material is selected from thegroup consisting of SiO₂, Al₂O₃, Cu, Ag and an alloy comprising Cu or Agas the main component.
 2. A master information carrier used forrecording information signals on a magnetic recording medium, comprisinga non-magnetic substrate having an embossed surface that forms a patternof recessed portions, the pattern being disposed in the track lengthdirection so as to correspond to uniform and non-uniform arrangements ofthe information signals; and a ferromagnetic film filled in the recessedportions of the pattern, top surfaces of the non-magnetic substrate andthe ferromagnetic films forming a substantially flat surface, whereinthe ferromagnetic film comprises a material selected from the groupconsisting of Co, Fe, and an alloy comprising Co or Fe as the maincomponent and the non-magnetic substrate comprises a material selectedfrom the group consisting of SiO₂, Al₂O₃, Si, and C.
 3. A method ofmanufacturing a magnetic recording medium comprising: bringing themaster information carrier according to claim 1 into contact with themagnetic recording medium; and applying a magnetic field, whereby themagnetic recording medium is recorded a magnetized pattern correspondingthe pattern formed on the master information carrier.
 4. A method ofmanufacturing a magnetic recording medium comprising: bringing themaster information carrier according to claim 2 into contact with themagnetic recording medium; and applying a magnetic field, whereby themagnetic recording medium is recorded a magnetized pattern correspondingthe pattern formed on the master information carrier.
 5. A masterinformation carrier used for recording information signals on a magneticrecording medium, comprising a non-magnetic substrate; a pattern offerromagnetic film which is disposed on the surface of the non-magneticsubstrate, the pattern being disposed in the track length direction soas to correspond to uniform and non-uniform arrangements of theinformation signals; and a non-magnetic solid materials filled inportions between the respective neighboring ferromagnetic films areascomposing the pattern, top surfaces of the ferromagnetic films and thenon-magnetic solid material forming a substantially flat surface whereinthe ferromagnetic film comprises a material selected from the groupconsisting of Co, Fe, and an alloy comprising Co or Fe as the maincomponent, and the non-magnetic solid material comprises a polymermaterial.
 6. A master information carrier according to claim 5, whereinthe polymer material is formed by diluting polyimide in a solvent toprepare a polyimide solution, spin-coating the polyimide solution, andcuring it with heat.
 7. A master information carrier according to claim1, wherein a protective film is formed on the surface of saidferromagnetic film and said non-magnetic solid material.
 8. A masterinformation carrier according to claim 7, wherein the protective filmcomprises carbon as the main component formed by sputtering.
 9. A masterinformation carrier according to claim 2, wherein the cross section ofsaid ferromagnetic film in a bit length direction of the informationsignals has a substantially trapezoidal shape with an upper side at thesurface that is longer than a lower side on the substrate.
 10. A masterinformation carrier according to claim 2, wherein a protective film isformed on the surface of said substrate and said ferromagnetic filmfilled in the recessed portions.
 11. A master information carrieraccording to claim 10, wherein said protective film comprises carbon asthe main component formed by sputtering.
 12. A master informationcarrier according to claim 7, wherein the protective film has athickness of 20 nm or less.
 13. A master information carrier accordingto claim 7, wherein the protective film is electrically conductive. 14.A master information carrier according to claim 10, wherein theprotective film has a thickness of 20 nm or less.